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Published on: July 13, 2012
Mixing effects on decentralized high-solid digester for horticultural waste: Startup, operation and sensitive
Liwei Mao1, To-Hung Tsui2, Jingxin Zhang3
1NUS Environmental Research Institute, National University of Singapore, 1 Create Way, Create Tower #15-02, 138602, Singapore; Energy and Environmental Sustainability for Megacities (E2S2) Phase II, Campus for Research Excellence and Technological Enterprise (CREATE), 1 CREATE Way, Singapore 138602, Singapore; Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117585, Singapore.
This study explored anaerobic digestion of horticultural waste using a high-solid digester with intermittent mixing. Optimal mixing strategies were identified for efficient start-up and continuous operation, impacting microbial community dynamics.
Area of Science:
- Environmental Science
- Biotechnology
- Waste Management
Background:
- Decentralized anaerobic treatment of horticultural waste is crucial for sustainable waste management.
- High-solid digesters offer potential for efficient organic waste processing.
Purpose of the Study:
- To investigate the effect of intermittent mixing on a horizontal high-solid digester for horticultural waste treatment.
- To determine optimal mixing strategies for digester start-up and semi-continuous operation.
Main Methods:
- Computational Fluid Dynamics (CFD) simulations for flow pattern and mixing time characterization.
- Experimental comparison of three intermittent mixing intervals (3 min/3 hr, 18 min/3 hr, 108 min/3 hr) and a control (no mixing).
- Analysis of digester performance and microbial community structure.
Main Results:
- Minimal mixing proved essential for efficient digester start-up.
- Increased mixing intensity was beneficial for semi-continuous operation.
- Specific microbial communities were sensitive to varying mixing intensities.
Conclusions:
- Intermittent mixing significantly influences the performance of high-solid anaerobic digesters.
- Tailored mixing strategies are required for different operational phases (start-up vs. continuous).
- Understanding microbial responses to mixing is key for optimizing waste treatment processes.
